How do I get Photos on macOS to search through photos for new faces

Photos is scanning the photos automatically for faces, right after you import the photos. But it is not automatically adding the detected faces to the People album. Initially, Photos will add just a few people to the People album, only people, where it found the same face in many photos. If you want more photos in the people album, do the following:

• Go to the "View" menu and enable "Show Faces names"
• Open a photo of the person you want to add to the People album, view it enlarged , and if the face has been circled as a detected face, enter the name of the person, to add it to the People album. Do this for all people, you want to see in the People album.
• To ensure, that the new photos of the people you already have named are added to the People album, open the album of each person in turn and use the command "Confirm additional Faces".